In recent years, it has been increasingly demanded that a large amount of file data, called, for instance, big data, be stored due to increased use of computers. Such demand is being met by improving the recording density of a storage. Further, as a large amount of file data often includes a considerable amount of file data having the same content, a technology for deduplicating file data having the same content at a node such as a file server has been under development.
As a deduplication technology, an inline deduplication technology and a post-process deduplication technology are disclosed in Patent Literature 1 (Paragraph [0025] and other parts).